Avalanche Forecast
Issued: Mar 6th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs, Wind Slabs and Loose Wet.
Conrad Janzen,
Cooler temperatures and less solar inputs on Sunday should further reduce the likelihood of triggering persistent slabs. However it is a big forecast region and there is still uncertainty as to how reactive these will be in different areas.
Summary
Weather Forecast
Clouds and light flurries are forecast for Sunday with a few cm's of accumulation starting late in the afternoon and evening. Alpine winds will be in the high end of Moderate from the SW which will help keep things cool but could move snow in the alpine. Treeline temperatures will be around -5 with valley bottom temperatures just above freezing.
Snowpack Summary
10-15 cm of new snow sits over a crust on solar aspects. Previous strong SW winds scoured alpine ridges and created wind slab in some alpine lee areas. Two persistent facet layers (Feb 19 & Jan 27) are down 30-80cm and still producing sudden shears in some locations. In thin areas the basal depth hoar/crust from Nov is still quite prominent.
Avalanche Summary
Small loose wet sluffs were observed on steep south aspects Saturday when the sun came out. No new slab avalanches were observed however lots of natural cornice, explosive, and some skier triggered avalanches, up to size 3, have been observed in the past four days during the big warm up. Most seem to be failing on one of the persistent layers.
Confidence
Timing or intensity of solar radiation is uncertain
Problems
Persistent Slabs
Two layers of facets and/or sun crust in the top meter of the snowpack have been active in the past week. Cooler temps and surface crusts formed over the last two days may reduce the likelihood of triggering at lower elevations and on solar aspects.
- Pay attention to overhead hazards like cornices which could trigger the persistent slabs.
- Use conservative route selection, choose moderate angled and supported terrain with low consequence.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Some wind slabs exist in lees of alpine features from previous strong winds. Recent cornice failures have also been observed. The wind slabs have been less reactive in the past two days but caution is still advised in steep lee areas.
Aspects: North, North East, East, South East.
Elevations: Alpine.
Likelihood
Expected Size
Loose Wet
The new snow is likely to sluff in steep solar terrain anytime the sun comes out and rapid heating occurs. This can be amplified in thin rocky areas. Watch for this in gullies or couloirs that have a solar aspect above them.
- Pay attention to sluffing off cliffs and steep solar terrain, signs of a warming snowpack.
- Watch for moist surface snow over crust on steeper solar aspects.
Aspects: South East, South, South West.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Valid until: Mar 7th, 2021 4:00PM
